01 Fundamentals of Networking

8/3/2019 01 Fundamentals of Networking

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CIM 2465 Fundamentals ofNetworking

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Fundamentals of Networking

(Topic 1)

Textbook:

Networking Basics, CCNA 1 Companion Guide, Cisco Press

Cisco Networking Academy Program, CCNA 1 and 2,Companion Guide, Cisco Press, Latest Edition


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2

Common Networking Icons


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3

Networks

A network is a set of devices (nodes)connected by media links. A node can bea computer, printer, or any other device

capable of sending and/or receiving datagenerated by other nodes on the network.The links connecting the devices are oftencalled communication channels.

E.g. two PCs connected with a cable, theInternet


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Requirements for Internet

Connection Physical connection

Network Interface Card (NIC)

Cable? Wireless

Logical connection A logical connection uses standards call protocols

A protocol is a set of rules and conventions thatgovern how devices on a network communicate

Transmission Control Protocol / Internet Protocol(TCP/IP) is a key protocol used in the Internet

Applications E.g. Web Browsers


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PC Basics

Transistor, Integrated circuit (IC), Resistor, Capacitor,CPU, memory etc.

Motherboard, Power Supply, Hard disk, CDROM, VideoCard, Sound Card, etc.

Serial Port, USB Port, Parallel Port Modem

A modem is an electronic device that is used for datacommunications through telephone lines

Network Interface Card (NIC)

An expansion board that provides a network communicationconnection to and from a PC.

Build in circuit

10 Mbps, 100 Mbps, 1000 Mbps

Media Access Control (MAC) address


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CIM 2465 Fundamentals ofNetworking 7


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Binary Representation of Data

Computers can only understand and use data

that is in binary (two-state, on/off, 0/1) format

Each binary digit is called a bit

Each grouping of eight bits is called a byte

Kilo (1024), Mega (1024*1024), Giga, Tera

American Standard Code for Information

Interchange (ASCII) is the most commonly usedcode for representing alphanumeric data in a

computer. E.g. 65 is A, 66 is B


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Base 10 Number System

Symbols: 0,1,2,3,4,5,6,7,8,9

2134 (decimal) = 2*103 + 1*102 + 3*101 + 4*100

Base

Exponent103 102 101 100

Place

Value1000 100 10 1

e.g. 2134 2*103 1*102 3*101 4*100


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Symbols: 0,1

10110 (binary) = 1*24 + 1*22 + 1*21 = 22 (decimal)

Base

Exp27 26 25 24 23 22 21 20

Place

Value128 64 32 16 8 4 2 1

e.g.

10110

0 0 0 1 0 1 1 0


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Symbols: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F

0A08 (hex) = 0*163 + 10*162 + 0*161 + 8*160

= 2568 (decimal)

Base

Exponent163 162 161 160

Place

Value4096 256 16 1

e.g. 0A08 0*163 10*162 0*161 8*160


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Converting Decimal Numbers to

Binary Numbers


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Converting Binary Numbers to

Decimal Numbers


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Converting Decimal to

Hexadecimal


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Converting Hexadecimal to

Decimal


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Converting Binary to Hexadecimal

Binary -> Decimal -> Hexadecimal

Short Cut: 4 bits -> 1 Hexadecimal digit


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Basic Logic Operations

AND OR XOR

0 0 0 0 0

0 1 0 1 1

1 0 0 1 1

1 1 1 1 0

NOT

0 1

1 0


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Types of Networks

Local Area Network (LAN) LAN is usually privately owned and links the devices

in a single office, building, or campus

Designed to allow resources to be shared

Metropolitan Area Network (MAN) Designed to extend over an entire city

May involve service provided by public companies,e.g. local telephone company

Wide Area Network (WAN) Provides long-distance transmission of data overlarge geographical areas

Virtual Private Network (VPN), Intranet etc.


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Local Area Network (LAN)

Designed to

Operate within a limited geographic area

Allow many users to access high-bandwidth media

Provide full-time connectivity to local services

Connect physically adjacent devices

Some common LAN technologies

Ethernet

Token Ring

FDDI


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Wide Area Network (WAN)

Designed to Operate over large, geographically separated areas

Allow users to engage in real-time communicationwith other users

Provide full-time remote resources connected to localservices

Provide e-mail, WWW, file transfer, e-commerceservices

Some common WAN technologies Modems, ISDN,

DSL, Frame Relay

T1 or E1 leased lines


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Virtual Private Network (VPN)

A VPN is a private network that is

constructed within a public network

infrastructure (e.g. Internet)

Provides a secure tunnel


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Bandwidth

The amount of information that can flow througha network connection in a given period of time.

Analogy: the width of a pipe, the number oflanes on a highway

Measurement: bps

Why important Bandwidth is finite

Bandwidth is not free

Bandwidth is a key factor in analyzing networkperformance and designing new networks

Demand for bandwidth is ever-increasing


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Throughput

Bandwidth of a LAN is usually 100Mbps,

can you transfer file at that rate?

Throughput refers to actual measuredbandwidth

Factors

Client, Server, Other users, Routing,

Topology, Type of data, Time of day


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CIM 2465 Fundamentals of

Networking

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Network Protocols (1)

Protocol suites are collections of protocols that

enable network communication from one host

through the network to another host

A protocol is a formal description of a set of rulesand conventions that govern a particular aspect

of how devices on a network communicate. It

determines the format, timing, sequencing, and

error control


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Networking

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Network Protocols (2)

Protocols are created and maintained by many

Standards organizations and committees

Institute of Electrical and Electronic Engineers (IEEE)

American National Standards Institute (ANSI)

Telecommunications Industry Association (TIA)

Electronic Industries Alliance (EIA)

International Telecommunications Union (ITU)

International Organization of Standardization (ISO)


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Networking

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Networking Models

Conceptual Model helps you understand the action that occurs during

communication from one computer to another

Network communications is a very complex process,

difficult to understand it as a whole, so break it down intoa series of layers

Each layer is responsible for a specific part of networkcommunication

Layers interact with the layer above and below them only

Two common models Open System Interconnection (OSI) reference model

TCP/IP reference model


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Networking

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OSI Model (1)

Released in 1984, by ISO

Provides vendors with a set of standardsthat ensure greater compatibility andinteroperability among various types ofnetwork technologies

Defines the network functions that occur at

each layer Acts as a framework for understanding the

network


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Networking

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OSI Model (2)

7 layers 7: Application layer

6: Presentation layer

5: Session layer

4: Transport layer

3: Network layer

2: Data link layer

1: Physical layer

Layer 5,6,7 are concerned with applicationissues

Layer 4,3,2,1 are concerned with data-transportissues


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Networking

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OSI Model (3)

Advantages of layering

Standardizes network components to allow

multiple-vendor development and support

Allows different types of network hardware

and software to communicate

Prevents changes in one layer from affecting

the other layers Breaks into smaller components to make

learning easier


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Networking

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Layer 7: Application Layer

Closest to the user

Provides network services to the users

applications E.g. telnet, http


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Networking

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Layer 6: Presentation Layer

Ensures that the information that the application

layer of one system sends out can be read by

the application layer of another system

Provides services to layer 7

Translates (if need) among multiple data formats

by using a common format

Encryption and Decryption E.g. layer 6 formats: TIFF, JPEG, MIDI, MPEG


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Networking

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Layer 5: Session Layer

Establishes, manages, and terminates

sessions between two communicating

hosts

Synchronizes dialogue between the two

hosts presentation layers and manages

their data exchange



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Networking

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Layer 4: Transport Layer

Segments data from the sending hosts system andreassembles it into data stream on the receiving hostssystem

Provides a data-transport service which handles issues

like Reliability of transport Establishment, maintenance, and proper termination of Virtual

circuits

Transport error detection, recovery, Information flowcontrol

Provides services to layer 5 E.g. Transmission Control Protocol (TCP), User

Datagram Protocol (UDP), Sequenced Packet Exchange(SPX)


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Networking

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Layer 3: Network Layer

Provides connectivity and path selection

(routing) between two host systems that

might be on separated networks

Concerned with logical addressing


E.g. Internet Protocol (IP), InternetworkPacket Exchange (IPX)


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Networking

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Layer 2: Data Link Layer

Provides reliable transit of data across aphysical link

Concerned with physical address, network

topology, network access, error notification,ordered delivery of frames, and flowcontrol

Provides services to layer 3 E.g. protocols include Ethernet, Token

Ring, ISDN, PPP, and Frame Relay


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Networking

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Layer 1: Physical Layer

Defines the electrical, mechanical,

procedural, and functional specifications

for activating, maintaining, and

deactivating the physical link between end

systems

E.g. voltage levels, timing of signal,

physical data rates, physical connectors,etc.


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Networking

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Peer-to-Peer Communications

Each layer of the OSI model at the source mustcommunicate with its peer layer at thedestination

The protocols at each layer exchangeinformation, called protocol data units (PDU),between peer layers

Layer 4 (Segments)

Layer 3 (Packets) Layer 2 (Frames)

Layer 1 (Bits)


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Networking

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Encapsulation


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Networking

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De-Encapsulation


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Networking

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Networking Devices (1)

Network Interface Card (NIC) Each carries a unique code, Media Access Control (MAC)

address

Repeaters

To regenerate and retime network signals, allowing them totravel a longer distance on the medium

Work at Layer 1, physical layer, of the OSI reference Model

Hubs To regenerate and retime signals, a common connection point

for devices in a network Connect segments of a LAN

No filtering, no switching, no routing

Work at Layer 1


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Networking

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Networking

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Bridges A Layer 2 device designed to create two or more LAN

segments, each of which is a separate collisiondomain

To filter traffic on a LAN to keep local traffic local(using MAC address) yet allow connectivity to othersegments

More intelligent than hubs, with filtering capability

Create more collision domains, allowing more than

one device to transmit simultaneously without causinga collision

Maintain MAC address tables (bridge tables)

Broadcast: to all segments, i.e. one broadcast domain


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Networking

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Networking

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Layer 2 Switches

Like bridges, switches connect LAN segments, use a

table of MAC addresses to determine the on which a

frame needs to be transmitted, and reduce traffic Operate at much higher speeds than bridges

(performed in hardware)

Consider each switch port is a microbridge, and gives

each host the mediums full bandwidth

(microsegmentation)

Broadcast: to all segments, i.e. one broadcast domain


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Networking

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Switch


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Networking

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Routers

Internetworking device that passes data

packets between networks based on Layer 3

addresses

Make decisions regarding the best path for

delivery of data (based on network addresses)

Examine incoming packets (Layer 3 data) Choose the best path

Switch them to the proper outgoing port


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Networking

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Voice gateway

For handling packetized voice and data traffic

Digital Subscriber Line Access Multiplexers

(DSLAMs) Used at the service providers central office for

concentrating DSL modem connections from homes

Cable Modem

Wireless Access Point

Many more


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Networking

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Network Topologies (1)

A network topology defines how computers,printers, network devices, and other devices areconnected

Describes the layout of the wire and devices and

the paths used by data transmissions Physical Topology

Refers to the physical layout of the devices andmedia

Bus, Ring, Star, Extended Star, Hierarchical, Mesh Logical Topology

Defines how the medium is accessed by the hostssending data

Broadcast, Token passing


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Networking

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Networking

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Bus

Connects all the devices using a single cable

Main cable segment must end with a

terminator

Adv?

Disadv?


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Networking

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Star

Made up of a central connection point that is a

device such as hub, switch, or router, where

all the cabling segments meet. Each host inthe network is connected to the central device

with its own cable

Commonly used in Ethernet LANs

Adv?

Disadv?


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Networking

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Ring Hosts are connected in a circle

Data frame travels around the ring, stopping at eachnode. If a node wants to transmit data, it adds dataand the destination address to it. The frame thencontinues around the ring until it reaches thedestination node, which takes the data out.

Adv: no collision

Single Ring (one direction) Vs Dual Ring (bothdirections, fault tolerance)

Usually logical in ring but physical in star


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Full-Mesh and Partial-Mesh

Full-mesh topology connects all devices to

each other for redundancy and fault tolerance

Adv?

Disadv?


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Logical Topology

How the hosts communicate across the medium

Broadcast

Data frame is broadcasted to all hosts No order that the stations must follow to use the network

Collision?

Token ring

Control network access by passing an electronic token

sequentially to each host

The host gets an empty token has the right to send data

Documents

01 Fundamentals of Networking